These intrinsically safe and nonincendive, loop-powered 1/8 DIN digital panel meters can be installed virtually anywhere to provide convenient and informative displays of any 4-20 mA signal. One of the most convenient features of these instruments is their dual line display which is typically used to display the process variable on the 5-digit alphanumeric top line and the units or a tag on the 8-digit alphanumeric bottom line. Another common setup is to display the input in one scale on the top line (such as feet) and another scale on the bottom line (such as gallons). Both of these lines use 14-segment, alphanumeric characters for clear indication of tags, units or alarm messages.

Further enhancing the display on these instruments is a 20-segment bargraph available on the PD6608 that also includes a numeric value of the percentage the bargraph represents. There is even a model that displays level in feet and inches for customers who prefer to see their levels represented that way rather than in decimal format.

These loop-powered meters can be installed virtually anywhere because they get their power from the 4-20 mA loop and therefore require no separate power source. And they only drop 1.5 V (4.7 V with backlight), so they add very little burden to the loop. Additional features that allow these instruments to be installed virtually anywhere include a NEMA 4X, IP65 front panel, an operating temperature range of -40 to 158°F (-40 to 70°C), conformally coated PCBs, and a backlit LCD that can be read in bright sunlight or dimly lit areas. Finally, they are intrinsically safe and nonincendive, so they can be installed in hazardous areas.

Free, PC-based, software that connects to the meter via a micro USB cable is available for programming and setup of the meters. In addition, the meter can be programmed, setup and operated via the four front panel buttons. Three of these buttons can be used as function keys. In addition, a digital input is standard and is particularly useful for remote reset of the alarms or to trigger an alarm.

All models come equipped with two open collector outputs and are available with two solid state relays and 4-20 mA analog output options. The open collector outputs are useful for alarm indication or pulse output. The relays can be programmed for alarm indication, on/off control, or pump alternation.

The Loop Leaders display provides multiple ways to help users understand and keep track of their processes. The most obvious is the dual line which typically allows the user to display a numeric value of the process variable on the top line and units and/or a tag on the bottom line. There is also a bargraph that includes a numeric value of the percentage the bargraph represents. Finally, to alert users to an alarm condition, the display can turn red and flash an alarm message.

Dual-Line Display with PV/Units/Tag/Bargraph

One of the most common configurations of these instruments is displaying the process variable on the top line and units and a tag toggling on the bottom line with a bargraph for additional clarity:

PV on the top line; units and tag toggling on the bottom line

Max/Min Display

The max & min readings (peak & valley) reached by the process can be displayed either continuously or momentarily:
1. Display momentarily by pressing the F1 key (default) or assigning to any of the other function keys or to the digital input in the User menu. Press Enter to lock/unlock max/min display.
2. Display continuously by assigning either display line to max/min through the Display menu.

Any of the F1-F3 function keys (buttons) and the digital input can be programmed to reset the max & min readings.

Feet & Inches Display with Bargraph

There are Loop Leader models available for users that prefer to see their level displayed in feet & inches instead of decimal format. These versions can display level to 999FT 11IN & 15/16 on the top line. The bottom line can toggle between a tag and units or if dual scale mode is used, can display the input in a different scale such as volume.

Level in Feet & Inches with Bottom Line toggling between volume (62,346), and units (Gallons)

Change Between Units without Needing to Re-Scale the Meter

It is possible to change the display units within the selected unit class without the need to re-scale the meter. When selecting a new unit from within the DISPLAY menu (e.g. changing from gallons (GAL) to liters (L)), the meter will automatically convert the display values to display the new unit. If entering a custom unit (CUSTM), a custom conversion factor will need to be entered.

To help users get a quick understanding of where their process is at, certain Loop Leader models are available with a 20-segment bargraph. This bargraph also includes a numeric value of the percentage the bargraph represents.

Bargraph Provides Quick Understanding

To help users get a quick understanding of where their process is at, certain Loop Leader models are available with a 20-segment bargraph. This bargraph also includes a numeric value of the percentage the bargraph represents. The bargraph can be programmed to represent the percent of PV1 or PV2 or it can be scaled to any range within the scale.

Dual-Scale Display Feature

Users can use the Loop Leaders dual-scale feature when they want to show the same input in two different scales. For instance, the following example shows an application where the Loop Leader displays the input in feet and gallons:

Display Feet & Gallons and Toggle Between Units

Predefined and Custom Units

The meter has six available preprogrammed unit classes, volume, height, temperature, pressure, weight, and rate. When the desired unit class or unit of measure within a class is not available, a custom unit may be programmed by using the (CUSTOM) menu.

Tare

The tare function zeroes out the display. In the case of scale weight, tare is used to eliminate container weight and provide net weight readings. The captured tare may be reset manually with any function key or digital input.

Alarms Indicated by Flashing Red Messages

When an alarm occurs, the Loop Leaders display can be programmed to turn red and flash an alarm message along with the process variable and an alarm indicator (!). (Alarm indicator symbols are not available on bargraph models) The Loop Leaders flashing red alarm message can be activated even if no relay or open collector is connected.

Outputs

Loop Leaders are available with two open collector outputs as standard and two solid state relays and 4-20 mA output as options. The open collector outputs and relays generally operate in the same manner, with the major exception being the open collectors are not available for pump alternation and the relays are not available with pulse features. The open collectors and relays can be controlled either automatically or manually. The alarm status (with flashing red message) will show on the display even with no output wired.

Two Open Collector Outputs

The Loop Leader is equipped with two NPN open collector outputs that may be set up for pulse outputs, alarms, timed pulses, stopwatch on/off, or disabled. Pulse outputs can be set to transmit the PV value (PV1 or PV2 if meter is in dual-scale mode). Output 2 may be used to generate a quadrature output based on the other open collector output. An output test mode is also selectable to generate pulses at a constant programmable frequency.

Two Optional Solid State Relays

The meter is optionally equipped with two solid state relays that may be set up for alarms, timer, stopwatch on/off, or pump alternation. The relays are rated at 250 VAC/DC @ 1 A for resistive loads and 75 VA @ 0.6 A, 250 VAC/DC max (Safe Area only) for inductive loads. Alarms are available based on the PV value or the digital input.

Loop-Powered Relay Alarm Trip

The Loop Leader, with its two solid state relays, can be used as a loop-powered relay alarm trip. The Loop Leaders two relays can be programmed for two different kinds of latching operation: Reset via momentary contact closure at any time or reset via momentary contact closure only after the alarm has cleared. And the Loop Leader's display can be programmed to turn red and flash an alarm message  something not found on most loop powered alarm trips.

Optional Isolated 4-20 mA Output

The isolated analog output signal can be configured to represent the process variable (PV1, PV2, or retransmit). While the output is nominally 4-20 mA, the signal will accurately accommodate underand over-ranges from 1 to 23 mA. The output can be reverse scaled such that the meters high calibration value outputs 4 mA and the meter's low calibration outputs 20 mA.

Resetting the Open Collectors and Relays

The open collectors and relays (alarms) may be programmed to reset in the following ways:
 Automatic (AUTO): Alarm will reset automatically once the alarm condition has cleared.
 Automatic/Manual (AUTO.MAN): Alarm will reset automatically once the alarm condition has cleared but can also be reset using the Enter button (or whichever function key is set to acknowledge) at any time.
 Latching (LATCH): Alarm must be reset manually and can be done so at any time. Press the Enter (ACK) button at any time to clear the alarm.
 Latching with Reset after Cleared (L-CLEAR): Alarm must be reset manually and can only be done so after the alarm condition has cleared. Press the Enter (ACK) button after the alarm condition has cleared to reset the alarm.

Approvals

All versions of these instruments are CE marked. The hazardous area versions of these instruments are UL and C-UL Listed as intrinsically safe and nonincendive and ATEX and IECEx Certified for Intrinsic Safety in Hazardous Areas (Gas Atmospheres). These versions are also UL and C-UL Listed under the UL 61010-1 General Safety Standard.

One of the most useful aspects of the hazardous area approvals is that these instruments are approved by UL as nonincendive so they can be installed in Division 2 areas with no additional protective devices needed.

METEX CORPORATION LIMITED

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Metex Corporation Limited has been providing superior products and services to the process control, chemical treatment, waste water, industrial and manufacturing industries for over 25 years. It is our goal to continually provide our customers with the best possible equipment, technology, and service.

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